Trace detection of SARS-CoV-2 N-protein by diamond solution-gate field-effect transistor

In this study, we introduced H-terminated diamond solution-gate field-effect transistor (H-diamond SGFET) to detect trace SARS-CoV-2 N-protein, which plays an important role in replication and transcription of viral RNA. 1-Pyrenebutyric acid-N-hydroxy succinimide ester (Pyr-NHS) was modified on H-diamond surface as linker, on which the specific antibody of SARS-CoV-2 N-protein was catenated. Fourier transform infrared spectrum, scanning electron microscope and energy dispersive spectrum were utilized to demonstrate the modification of H-diamond with Pyr-NHS and antibody. Shifts of I_DS(max) at V_GS = -500 mV in transfer characteristics of H-diamond SGFET was observed to determine N-protein concentration in phosphate buffer solution. Good linear relationship between I_DS(max) and log₁₀(N-protein) was observed from 10^-14 to 10^-5 g/mL with goodness of fit R² = 0.90 and sensitivity of 1.98 μA/Log₁₀ [concentration of N-protein] at V_DS = -500 mV, V_GS = -500 mV. Consequently, this prepared H-diamond SGFET biosensor may provide a new idea for diagnosis of SARS-CoV-2 due to a wide detection range from 10^-14 to 10^-5 g/mL and low limit of detection 10^-14 g/mL.